A conventional particulate matter sensor detects particulate matter (hereinafter referred to as “PM”) in exhaust gas and thereafter burns the PM accumulated on an element unit of the particulate matter sensor to remove the PM (refer to PTL 1). At this time, the temperature of the element unit of the particulate matter sensor is controlled to be in a predetermined temperature range for burning PM. The particulate matter sensor described in PTL 1 maintains the temperature of the element unit in the predetermined temperature range until the internal combustion engine is stopped after PM is burned and removed. Therefore, the accumulation of PM on the element unit can be reduced after PM is burned and removed. Thus, the next time the internal combustion engine is activated, the particulate matter sensor can start to detect PM without burning PM.